The atmospheres filling massive galaxies , groups , and clusters display remarkable similarities with rainfalls . Such plasma halos are shaped by AGN heating and subsonic turbulence ( \sigma _ { v } \sim 150 km s ^ { -1 } ) , as probed by Hitomi . The new 3D high-resolution simulations show the soft X-ray ( < 1 keV ) hot plasma cools rapidly via radiative emission at the high-density interface of the turbulent eddies , stimulating a top-down condensation cascade of warm , 10 ^ { 4 } K filaments . The ionized ( optical/UV ) filaments extend up to several kpc and form a thin skin enveloping the neutral filaments ( optical/IR/21-cm ) . The peaks of the warm filaments further condense into cold molecular clouds ( < 50 K ; radio ) with total mass up to several 10 ^ { 7 } { M _ { \odot } } , i.e. , 5/50 \times the neutral/ionized masses . The multiphase structures inherit the chaotic kinematics and are dynamically supported . In the inner 500 pc , the cold/warm clouds collide in inelastic way , mixing angular momentum and leading to chaotic cold accretion ( CCA ) . The black hole accretion rate ( BHAR ) can be modeled via quasi-spherical viscous accretion , \dot { M } _ { \bullet } \propto \nu _ { c } , with clump collisional viscosity \nu _ { c } \equiv \lambda _ { c } \sigma _ { v } and mean free path \sim 100 pc . Beyond the inner kpc region , slow pressure torques drive the gas angular momentum transport . In CCA , the BHAR is recurrently boosted up to 2 dex compared with the disc evolution . The disc arises via helical condensation as turbulence is subdominant ; with negligible rotation too , the molecular phase is prevented via compressional heating . The CCA BHAR distribution is lognormal with pink noise power spectrum \propto f ^ { -1 } characteristic of fractal chaotic phenomena . The rapid self-similar CCA variability can explain the light curve variability of AGN and HMXBs . An improved criterium to trace thermal instability , or better , nonlinear condensation is proposed : \sigma _ { v } / v _ { cool } \lesssim 1 . The 3-phase CCA reproduces crucial observations of cospatial multiphase gas in massive galaxies , as Chandra X-ray images , SOAR H \alpha warm filaments images and kinematics , Herschel [ C ^ { + } ] emission , and ALMA giant molecular associations . CCA plays key role in AGN feedback , AGN unification/obscuration , the evolution of BHs , galaxies , and clusters .